Electric furnace for metallurgical purposes.



H. P. D. SGHWAHN. ELECTRIC FURNACE FOR METALLURGICAL PURPOSES. APPLICATION FILED MAR.24. 1909.

962,532. Patented June28, 1910.

UNITED STATES PATENT our-ion HEINRICH F. DISCHWAHN, OF IBELLEVILLE, ILLINOIS ELECTRIC FURNACE FOR METALLT IBGICALPURPOSES.

Application filed March 24, 1909. Serial No, 485,503.

To all whom it may concern:

Be it. known that I, HEINRICH F. D. SCHWAHN, a citizen of the United States, and resident of the city of Belleville, in the county of St. Clair and State of Illinois,

have invented certainnewand useful Improvenients in Electric Furnaces for Metallurgical Purposes, of, which the following is an exact description.

This invention is an electric furnace ca-- pable of general use and especially suitable for the reduction, fusion and treating of metals, and the manufacture of aluminum and its alloys.

The construction of thefurnace is shownv in the accompanying drawings in which;

Figure-1 is a vertical axial section, taken through the angular groove of the retort, showing the furnace provided with a mantle and a conical core made of refractory material; Fig.2 is a vertical axial section in a plane at right angles to that of Fig. 1, taken through the tap-hole of the retort, showing the furnace provided with a water cooled mantle and cone; Fig. 3 is a horizontal section on lines IIIIII Figs. 1 and 2; Fig. 1.

is a plan view; Fig.- 5 is a detail perspective view'of a carbon electrode for the conducting of an alternating electric current, showing the two parts or layers of difierent com position.

The furnace consists of an annular chainber comprising two distinct "working parts, the retort 1 as the lower section and the gaschamber 2 as the upper'section, and the en-' tire apparatus is mounted on a suitable base 3. In the space 4 surrounded by the retort 1 is centrally located an alternating electric step-down transformer 5. Said transformer is surrounded by a mantle 6 .consisting of a cylinder suitably made ofv fire clay and closed on its upper end, this mantle leaving a dead-air space 7 between'itself and the inner wall of the retort 1', and an open space 8 around the transformer 5 for the circulating of air 'passing through conduit 9 of the transformercore 10' from pipe 1-1 connected with .said conduit9.- Said air after passing over the transformer 5 with its primary coil 12 and secondary coil 13 will find its way out from said space 8 through the apertures 14: of base 3. Said air is used for the'cooling of the transformer and may be supplied to pipe 7 11 by any suitable means.

The lower section of the furnacefcontaining the retort maybe suitably built of sultably prepared magnesite within the inclosing shells 15 and 16, said shells are prefer ably made of copper. The lower part of the retort l or its hearth 17 is partially formed of Specification of Letters Patent. Ptenigefl Jun 28, 1910, V

the electrodes 18 and 19 being in part resistance conductors, which have terminal con-" nections 20 of highly conductive material;

These electrodes are shown here .as made of one block of carbon, and each of these car:

,bon-blocks made of two parts or layers 21 and. 22, the part 21 being the resistance conductor and terminal, while the part 22 is of the highest conductivity suitably connected with the carbon rod 20, which extend through the bottom of thev furnace to make terminal connection by means of the copper bars 23 andQArespectiVely with the second- .ary coil 13 of the transformer 5. These electrodes, shown in Figs. 1, 3 and 5, are

most suitably made of an electric carbon composition as usually made of oil coke and tar, and from two different mixtures suit-r ably molded together or otherwise suitably carbon and bring it into an incandescent condition for the heating of the furnace and its starting for operation, while the lower part 22 ismade' for obvious reasonas usual of a mass of the highest conductivity, and

said carbon electrodes are then finished as usual by superheating. These electrodes 18 and 19 are embedded in the hearth of the retort 1 as usually practiced in the operation of electric furnaces and are protected by the refractory and nonconductive material of the furnace leaving only one side or the part flush with the hearth 17 exposed. The

connection of these electrodes with the copper bars 23 and 24: may be made in any suitable way here shown as made by split collars and clamps.

In'the upper part of the retort 1 flush with its sides are embedded another set of electrodes -or terminals 25 and 26 made of metal, suitably copper or aluminum,-sa1d terminals are cored for the circulating of 'and open into the retort ata tion of reducing or fiuxing gases.

water and cooling of said electrodesf These electrodes have terminal connections 27 and 28 respectively with a direct current generator, not shown. However said electrodes may be also connected with the transformer 5 if desired, and used in conjunction with the carbon electrodes 18 and 19 by clamping the said electrodes 25 and 26 by their termi- 112115 27 and 28 to the copper bars 23 and 24; respectively. In the lower part of the retort as shownin Fig. -1 is a right angular groove 29, the vertical inner portion of which communicates with a passage or out let 30 extending through the side of the retort near its base. preferably of graphite crucible composition extend through the outer wall of the furnace point slightly 26 as herein the introduc- A taphole 32 is also provided at the base of the retort as shown in Fig. 2 for the .emptying of the retort of its entire contents if desired.

The upper part or gas-chamber 2 is above the electrodes 25 and shown. These pipes serve for formed by the mantle 33 and cone 34 and both are suitably removably constructed" either .of refractory material as shown in Fig. 1, or of water cooled copper shells as shown in Fig. 2. This mantle 33' serves to exclude the outer air, to carry olf the spent gases by means of pipe 35, said pipe 35may be used in plurality if desired for the-carrying off and depositing of heavy metallic vapors as shown by pipe 36 in Fig. 2, said pipesmay enter into any suitable appliance for-the recovery of said metallic vapors as usually used for this purpose. This mantle-33 is further provided with a hopper 37 suitably controlled by the usual bell 38 for'the charging of the green material upon the cone 34L centrally located b'elow said hopper 37 and above'the transformer5 as shown in Figs. 1 and 2. B

this arrangement it will be noticed that the charges are evenly distributed over said cone 34 into the gas-chamber 2 and retort I. Said chamber 2 is not intended to be usedonly for the excluding of the outerair, feeding of the retort 1 and the carrying off of the noxious spent gases and metallic Vapors but also for a repository of the charge to be acted upon'by said reducing and 'fluxing gases, abo e re erred to, chemically and in conjunct on with the radiant heat fromthe retort below, as required for the preparation of some ores or metallic compounds previous to their reduction. 39 and 40 indicate the water pipes of the electrodes 25 and 26 respectively.

The mantle 33 and cone 34 if made ofrefractory material may be suitably strengthened each separately by a metallic skeleton indicated by a and b suitably made of bronze or copper, suitably extending from circular A plurality of pipes 31,.

@lso be used without the desired, or if the furnace shall be used only 6 for the remelting, metals.

In the operation-of the furnace a pool of metal and slag, or bath of fluorids etc.

treating and alloying of is maintained in the base or hearth of the retort, and to such height as to till the outlet 3O thereby excluding the outer air from the retort and incandescent electrodes 18 and-l9, and establishing the electric circuit between these alternating current terminals,

andiffilled with more conductive material, up to the electrodes 25 and 26 a circuit of .thedirect electric current is established and both currents may flow then side by side and act upon the charged material by heat and g electrolysis in conjunction with the introduced reducing and fiuxing gases if desired. The excess of metal or. other molten product resulting from the operation of the furnace continuously overflows through the groove 29. This tap-device may be, if desired, more or less closed suitably by a plug to enable the production of a higher or lower level of the molten product within the retort, or the carried out from the tap-hole 32. spent gases are allowedtq escape through pipe 35, the hopper 37 being normally closed during the operation of the furnace, as by the bell 38 operated by the lever i1.

This furnace is more especially intended for the production of aluminum by the proc esses, described in my Letters Patent of F ebr. 3, 1903, N o.,7l9,698. ;an applicationSerial No. 466,255, filed application Serial No. 514,628, filed Aug. 25, 1909in which is set forth the possible production of alumina from sulfate of aluminum and its reduction in one operation by and discharges tapping may be Dec. 7, 1908, and in an means of this'furnace'and reducing gases upon or above and in the usual bath of fiuorids. Reduction is principally efiected the use of a gas and inthese processes by first upon the alumimoderate heat actingnous compound but the electric current may be employed to furnish this, and-thenfinish the reduction in heating the charge to the temperature ofreaction or action by electrolysis,--or both together, which is the more desirable and cheapest.

direct electric current oronly with the latter, the improvement,may be also used for the reduction, treatment or alloying of any other'metal The furnace may than aluminum, especially volatile metals such as zinc.

The underlying principles of this furnace may be said to consist, (l) in the shortening of the distance of conductlng'the converted current to its place of action, (2) in theemployment of resistance conductors as tertransformer with 'a'winding in proportion by which the furnace and the chargedmaincidentally a bath, and thereby completing with similar results as obtained in furnaces of iron and ccpper'and in the windings to i 7 other suitable way and manner.

over a wide area with the possible confining about 2 turns of the secondary coil, whereby current is established, namely that of heat- -my purposes a transformer of the open trodes is omitted"; (2) the subduing of the extreme revolving motion by the action of convey electric currents when highlylheated by Rochling in operating his induct on furminals for. the alternating current from a of about 100 turns of the'primary coil.to

a double action or flow of the alternating ing by resistance (1 R in the terminals and terial' is heated and fused thereby producing,

the secondary Winding of the transformer,

of the induction type which has been found to be correct; and I preferably use for circuittype, suitably proportioned in weight get the'bestresults. However, itis imma-, terial whether the carbon electrodes 18 and 19 are locatedin the hearth of the furnace or in its side-walls, or are introduced in any- The essential features of this improvement are: '(1) the arrangement of the fur na'ce' and electrodes or electric terminals for the heating ofthe-furnace and reducing and, fusing of the charge by the combined ac-' tion of alternating and direct electric currents and reducing gases whereby the vuse of them expensive carbon rods for electhe secondary electric current upon the-bath of molten metal etc. as experienced in the ordinary induction furnace so injurious to its trough, by means 'of the currents con ducted into the bath through the resistance conductors or terminals directly from the transformer and the terminals of the direct current generator; and highelectrical and thermal actionandits even distribution by a charge of molten metal, as practiced nace, for heatingand treating iron to produce steel thereof. a v The construction of furnace shown is capable of modification, within the scope of theclaims.

I claim Y 1. An annular electrie furnace around-an number "of said electrodes comprisin two parts, one of which is highly con uctive electric current transformer said furnace provided with electrodes consisting. each of' two parts one part of which is made substantially of pure carbon, while. the other part being its terminal is made of carbon com-' pounded with a suitable refractory material to give it adequate resistance to an electriccurrent secured from said transformer, substantially as and for the purpose set forth. 4

' 2. An annular electric furnace having an alternating electriccurrent transformer. located in ts center, said furnace prov ded with a plurality: of "electrodes, one number of said electrodes comprising each two parts, one of which is highly conductive for electricity while the other part is a resistance conductor being the electric terminal con-.

meeting by said highly conductive part with 5 said transformer, while another numberv of said electrodes are normally good conductors-for electricity and connectin with a direct current generator, as set fort t 3, An annular electricfurnace around an electric current transformer, said furnace provided with a plurality of electrodes, onle eac for electricity while the other part being its terminal is a resistance conductor-and extending over a' major part. of the'hearth of said furnace, while another number ofsaid electrodes are arranged to .be conductive throughout, substantially as and for the purpose set forth. 1

' 4. An annular electric furnace upon a suitable base, said furnace comprising two Working-parts registering into each. other,

the lower part of which consists of an annular retort provided with suitableelectric' terminals, gas-inlets'and metal and slag o'utlets,-said annular retort inclosing an alternating electric current transformer connecting with said electric terminals, while theother and upper working part consists of an annular cdnical gas-chamber with a conical core in its center, said cone located over and; above said transformer, said as-chamber be-' ing provided with a suitable hopper centrally located over and above said cone-for the char 'ng of the, furnace, and suitable outlets or the spent gases and metallic vapors for-their recovery, as set forth.

'5. An annular electric furnace comprising an upper chamber for the preparing of the mater-1al, and' a lower chamber for the reduction of said material, said chambers regv istering into each other and inclosing an alternating electric current transformer, said -lowerchamber having suitable gas-inlets, suitable electric terminals, an; opening near 'its base and an angular passage extending upwardly and outwardly-from said opening as an outlet for the furnace product, said upper chamber havingiasuitable hopper and gas-outlets, as set fort current transformer, said. chamber suitably decreasing upwardly in size slightly from above. said transformer to form an annular conical upper chamber removably arranged,- said'conical chamber provided with suitable means for the charging. of the furnace and discharging of the spent gases and metallic vapors, while the lower part being the lower chamber and retort is provided with a pluthe secondary coil of said transformer,= as

rality of electric terminals connecting with set forth.

7. An electric furnace having a plurality ofelectrodes, one number of said electrodes consisting of an electric resistance conductor embedded in the furnace wall substanvtially flush with its hearth, while another number of electrodes are made of metal, cored and cooled by water and are embedded in the furnace walls, substantially flush with their inner sides above said hearth, as set forth.

8. The herein described electric furnace,- which consists in an annular furnace'chamber upon asuit-able base, said chamber inclosing an alternating electric current transformer, .a cone shaped removable mantle over and above saidchamber and a conical core within said mantle removably arranged over and above said transformer, and thespace between said mantle andcore forming .'a continuation of saidchamber, as set forth.

'9. The herein described' -electric furnace which consists of an annular furnace cham her the upper part of which is removably arranged and suitably made of metal,,cored and cooled by water, while its lower part is arranged stationary and is substantially made of-refractory material and inclosing an alternating current transformer.

HEINRICH RD. SCHWAHN. Witnesses:

- EDMUND BURKE,

EDWARD WV. WEST. 

